[sdiy] Re: Saw phase shifter was: English lessons

[Harry Bissell Jr]

Yes you can sweep the phase with CV

By dependant on power supply voltages, Magnus'
version relies on the clippling of the opamp to
get the shift. So if the opamp does not clip politely
or if the supply voltage changes, you will be out
of calibration.

Likewise if the Sawtooth amplitude in changes, you
will be out of calibration as well.

It would be possible to make a precision clipper to
get
around this problem.  If the sawtooth does not have
fast reset time, there will be a major glitch in the
wave. Trying to filter this without killing the normal
reset of the saw is difficult.

I think that having individual harmonics able to be
phase shifted might be underwhelming. It could be done
but humans are not super sensitive to pahse of
harmonics (unless they are shifting) which would seem
to be the point here. 

H^) harry

--- mark verbos <mverbos at earthlink.net> wrote:


---------------------------------
    wait, you can sweep the phase 360 degrees with a
CV? That's what Imean. I thought you had to trim it in
and leave it. Didn't you say thatit was dependent on
power supply voltages?

anyway, the Buchla thing (and he only made one like
this, so he learnedhis lesson) as far as I understand
it, has the root and the next 9harmonics in sine
waves. Those sine waves can be swept 360 degrees
andhave their volumes mixed. I think this is a big
difference from justhaving the sines all starting at
the same place, but maybe I'm kiddingmyself. 

you're right it's not MORE important.  :(

Mark


Harry Bissell Jr wrote:
  
MORE importantly... (what are you saying ?)The phase
voltage 'is' sweepable isn't it ?If you mean that
changing the voltage changes therelative phase shift
of the sawtooth.The neat thing would be to be able to
sweep overmultiple cycles.I'm using sawtooth phase
shift now.  It sounds good,but if you compare it with
the input sawtooth itsboring. The sound would be more
like a simple PWMwave.So what do you mean ???H^)
harry--- mark verbos <mverbos at earthlink.net> wrote:  
      
more importantly, how do you make the phase
voltagesweepable? You need to put the Buchla harmonic
generator in MillsCollege to shame.MarkMagnus
Danielson wrote:    
          
OK, now to get you back on track... remember my      
        
sawtooth phase-shifter? What do    
          
you guys think needs to be done to make it      
        
workable? Should a good op-amp be    
          
enought maybe?Cheers,Magnus